Refrigeration system employing expendable refrigerant



Dec. 29, 1964 F. w. HOTTENROTH 3,163,022

REFRIGERATION SYSTEM EMPLOYING EXPENDABLEI REFRIGERANT Filed Jan. 21,1963 J12 22222 for F 524 m MfKdZv/ZL United States Patent C) 3,163,022REFRIGERATIGN SYSTEM Ell KPLOYIWG EXPENDABLE REFRIGERANT Fred W.Hottenroth, Palos Verdes Peninsula, Caiiil,

assignor to Z. Z. (Iorp ompton, Qalifi, a corporation of CaliforniaFiled Jan. 21, 1963, Ser. No. 252,686 9 Claims. {CL 62168) Thisinvention relates to a system used for the refrigeration of foods andthe like during transportation, and in storage.

One object of the invention is to provide a relatively simple yeteffective system for utilizing expendable refrigerant as a refrigeratingmedium at regulated temperatures. Such refrigerant may be Dry Ice,liquid carbon dioxide, liquid nitrogen or any expendable liquid, and mayeven be water at low barometric pressures, for instance in spacevehicles.

Another object is to provide a system in which the refrigerant is sealedwithin a refrigerant compartment so that it develops pressure asvaporization of the refrigerant occurs, and in which that pressure isutilized as a means to circulate gas through a cooled or refrigeratedcompartment for greater efliciency in extracting heat from the contentsof such compartment.

Another object is to provide an aspirator actuated by the pressure ofthe gas given off by the refrigerant as it vaporizes in the refrigerantcompartment, such gas being vented through the aspirator to drawadditional gas along with it from the refrigerated compartment, both therefrigerant gas and the additional gas then being returned to therefrigerated compartment to lower its temperature.

A further object is to provide a circulating system for gas which iscooled by the refrigerant wherein the circulating system includes acooling conduit that passes through a cooled compartment and absorbsheat therefrom to effect the cooling thereof.

Still a further object is to provide means for venting excess gas fromthe cooled compartment or from the circulation system.

An additional object is to provide a system of this kind which isautomatically controlled in accordance with temperature within thecooled compartment by means of a temperature responsive valve for theaspirator,

Another additional object is to provide means for relieving excess gaspressure from the refrigerant compartment when the aspirator is closed.

\Vith these and other objects in View, my invention consists in theconstruction, arrangement and combination of the various parts of myrefrigeration system, whereby the objects above contemplated areattained, as hereinafter more fully set forth, pointed out in my claimsand illustrated in detail on the accompanying drawing, Wherein:

FIG. 1 is a diagrammatic view of a refrigeration system embodying myinvention;

FIG. 2 is a similar view showing a modification thereof, and

FIG. 3 is a fragmentary view of a modification of a temperatureactivated control for the system.

On the accompanying drawing I have used the reference numeral It toindicate a refrigerated or cooled compartment in which food or the likeis contained, either for stationary storage or for transportation. Anexpendable refrigerant compartment 12 is provided within a circulationcompartment 13, and the compartments 1t and 13 are connected together bya supply conduit 14 and a return conduit 15. A supply of Dry Ice orother expandable refrigerant 15 is located within the compartment 12(which acts as a heat exchanger) and an aspirator in the form of a gasnozzle 13 discharging from the com- 3,163,622 Patented Dec. 29, 1964partment 12 and a Venturi restriction 20 in the conduit 14 is providedas illustrated.

As the refrigerant 15 vaporizes Within the compartment 12 the gasgenerated thereby is discharged from the gas nozzle 18 and by Venturiaction the aspirator 1840 induces a circulation of the gas through thecooled compartment 10 through the conduits 16 and 14 as indicated byarrows. The excess pressure caused by the conversion of the refrigerantto gas is relieved by discharge of the gas to atmosphere through a vent21.

The aspirator-induced circulation brings warm air from the productswithin the cooled compartment 19 into contact with the refrigerantcompartment 12 so that heat is absorbed therefrom by vaporization of therefrigerant and an effective circulation through all parts of the cooledcompartment is had by reason of such aspirator action.

By way of example, if the cooled compartment 19 is to be maintained at atemperature of 50 F., external heat would tend to make the temperaturerise and this in turn would be balanced by the flow of cooling gas intothe com partment. The gas from the cooled compartment as it passesthrough the return conduit 16 is slightly warmer than the desiredtemperature so it passes into the compartment 13 around the compartment12 Where it is cooled before it passes back through the conduit 14 intothe cooled compartment. Since the gas given off by the refrigerant 15increases the total amount of gas in the system, and this increase ingas must be disposed of, it is vented as described.

If automatic control is desired for the refrigeration system disclosed,it may be attained by means of a thermostatic valve 28 for the flow ofgas from the nozzle 18. The thermo-responsive element 29 of this valveis responsive to temperature within the compartment iii and for thispurpose has a temperature sensing bulb 34 mounted therein. Alternativelythe element 2% may control a valve in the conduits 14 or 15 and thus thefiow of gases there through.

In operation, the thermostatic valve 28 may be set at the desiredtemperature and when the temperature within the compartment 1% falls tothat value, the valve 28 will close. Thus the circulation of cooled gasis no longer induced by aspirator action until such time as thetemperature Within the compartment rises sufficiently to again open thevalve 28. The excess pressure that builds up within the refrigerantcompartment 12 when the thermostatic valve 28 is closed may be relievedthrough a safety valve such as one of the pressure relief type shown at32. The thermostatic valve controls the temperature by controlling theamount of gas flowing from the refrigerant compartment 12 through theaspirator 1840. The pressure relief valve 32 is set at a value higherthan the pressure that would be necessary to maintain the desiredoperation.

The compartment 12 is preferably formed with a heat exchange surfacesuch as metal. Due to the gas circulating around it, the refrigerant 15vaporizes at a rate fast enough to develop a pressure of about 2 p.s.i.in one installation which I have tested using Dry Ice. This pressure isenough to provide an adequate circulation through the cooled compartmentto drop its temperature well below 0 F. in less than two hours.

The combination of heat exchange surface and aspirator effect aremutually corelated. If the aspirator does not provide enough circulationwith the available pressure, there will not be enough gas flow over theheat exchange surface to vaporize enough Dry Ice to provide enoughpressure for the aspirator. If, on the other hand, the aspirator iseflicient and provides a good circulation, and the heat exchanger takesenough heat out of the circulated gas, there will be an excess ofpressure developed to take care of all requirements. This then permitsadetransmitted to it from the outside air regardless of howv well theparts are insulated. Both the compartments and 13 are illustrated asbeing insulated and the conduits 14 and 16 would also be suitablyinsulated for maximum efficiency. Vaporization of the Dry Ice starts tobuild up a pressure which in turn is vented through the aspirator. Thegas coming out of the aspirator draws in an additional amount of gaswith it and causes a circulating flow of gas through the refrigeratedchamber and back over the heat exchanger surrounding the Dry Ice whichis cooled thereby and in turn heats the Dry Ice thereby causing afurther amount of gas to be evolved from the Dry Ice. This further gasthen passes through the aspirator and cools down the refrigeratedchamber.

In the event it is undesirable to have actual contact of the gasdrivenoff the Dry Ice or other refrigerant used with the products within thecooled compartment 10, a cooling'coil 22 as shown in FIG. 2 may bearranged to connect from the supply conduit 14 to the return conduit'16, and a vent as may extend therefrom to atmosphere.

' If desired, fins 24 may be provided on certain portions of the coolingcoil 22 to increase its heat pick-up capability.

FIG. 2 shows a combination in which the gas after leaving the aspiratorsection passes through a secondary heat exchanger 22 to cool off therefrigerated chamber and then recirculates back over the heat exchanger12 in similar fashion to that described for FIG. 1. the air in thechamber from being contaminated by any gas that is used as arefrigerant. In both cases vents are provided so that the excess gaswhich is continually added by vaporization of the refrigerant isventedfrom the system. At the time it is vented, it has absorbed a maximumpractical amount of heat from the refrigerated chamber since it is notdischarged at the very low temperature which is given off by therefrigerant but has reached the temperature of the refrigerated chamber.

The thermostatic valve 28 regulates the amount of circulating gasthrough the system. The location of the parts may be such that thethermostatic valve on the aspirator is operated by a remote bulb sensingthe actual' gas temperature in the refrigerated chamber. An alternativemethod is shown in FIG. 3 wherein-a temperature sensing bulb 34 islocated in the return conduit 16 instead of within the chamber 10, andthe bulb 34 senses the temperature of the return gasfromthe refrigeratedchamber before it goes into the heat exchanger 12. The return gas atthis point should be a good average of the temperature of therefrigerated chamber.

It will be noted that I have referred to gas in the V refrigerationsystem disclosed. Actually, starting out with air therein, there atfirst is circulation of air, but over a period of time the air iscompletely driven out through the vent 21 and is entirely replaced bythe carbon dioxide gas. For this reason the use of the word gas isintended to cover'air as well as gas or a mixture of the two; 3

With respect to substituting a refrigerant such as liquid 7 carbon"dioxide or liquid nitrogen for the Dry-Ice 15, this is'readilyaccomplished by placing an open top container of the liquid in thecompartment 12. The liquid starts evaporating whenever heat above itsevaporating temperaturereaches it, and as soon as an inadequate amountof heat is supplied the evaporation stops. the refrigerant is at atemperature matched to its vapor pressure and evaporation isself-regulating in the same manner as Dry Ice.-

This keeps From the. foregoing specification, it will be obvious that Ihave provided a comparatively simple refrigeration system utilizingexpendable refrigerant, the refrigerant being used in proportion to thetemperature requirements of the produce being cooled, the thermostaticvalve 28 being set in accordance with such requirements. Withoutthermostatic control the system is self-regulating to a specifictemperature which is a function of aspirator performance. The aspiratordesign is merely varied to secure the desired results.

Some changes may be made in the construction and ararngement of theparts of my refrigeration system without departing from the real spiritand purpose of my invention, and it is my intention to cover by myclaims any modified forms of structure or use of mechanical equivalentswhich may reasonably be included within their scope. V

I claim as my invention:

1. In a refrigeration system, a compartment to be cooled, an expendablerefrigerant compartment, a circulation compartmentsurrounding saidexpendable refrigerant compartment and in heat exchange relationthereto,

a supply conduit from said circulation compartment to said cooledcompartment, 21 return conduit from said cooled compartment to saidcirculation compartment,

At this time aspirator means in the conduit system for circulating gas 1from said return conduit through said circulation compartment and saidsupply conduitto said compartment to be cooled, said aspirator meansbeing actuated by gas discharged from said expendable refrigerantcompartment, and a vent for excess gas from the circulation system. a

2. A refrigeration system according to claim 1 wherein said gas fromsaid supply conduit is circulated by said aspirator means directlythrough said compartment to be cooled and returns to said returnconduit, and said vent communicates with said compartment to be cooled.

3 A refrigeration system according to claim 1 wherein a cooling coil isprovided within said compartment to be cooled and receives cooled. gasfrom said supply conduit andreturns it to said return conduit, thusisolating the same from the contents of said compartment, and whereinsaidvent communicates with said'cooling coils 4. A refrigeration systemaccording to claim 1 having thermostatic valve means for controlling theflow of gases through said supply and return conduits, said thermostaticvalve means being responsive to the temperature of the .gas Within saidcompartment to be cooled after it has thermostatic valve meansforcontrolling the flow of gases through said supply and returnconduits, said thermostatic valve means being responsive to thetemperature of the gas being circulated." V l I 7. A refrigerationsystem according to claim 2'having a thermostatic valve for' controllingthe action of said aspirator means, said thermostatic valve means beingresponsive to the temperature of the gas being circulated,

and a pressure relief valve communicating with pendable refrigerantcompartment.

8. Arefrigeration system according to claim 3 having thermostatic valvemeansfor controlling the flow of gases said exthro g said Supply andreturn conduits, said thermostatic valve means being responsive to thetemperature resulting from heat absorbed from the contents of the cooledcompartment.

9. A refrigeration system according to claim 3 having thermostatic valvemeans for controlling the action of said aspirator means, saidthermostatic valve means being responsive to the temperature resultingfrom heat absorbed from the contents of the cooled compartment, and apressure relief valve communicating with said expendable refrigerantcompartment.

References Cited in the file of this patent UNITED STATES PATENTSFriedman Mar. 11, 1941 Smith Nov. 3, 1942 Brown Feb. 27, 1951 Hesson etal June 20, 1961 FOREIGN PATENTS Denmark Jan. 10, 1934 Great BritainJune 22, 1933

1. IN A REFRIGERATION SYSTEM, A COMPARTMENT TO BE COOLED, AN EXPENDABLEREFRIGERANT COMPARTMENT, A CIRCULATION COMPARTMENTS SURROUNDING SAIDEXPENDABLE REFRIGERANT COMPARTMENT AND IN HEAT EXCHANGE RELATIONTHERETO, A SUPPLY CONDUIT FROM SAID CIRCULATION COMPARTMENT TO SAIDCOOLED COMPARTMENT, A RETURN CONDUIT FROM SAID COOLED COMPARTMENT TOSAID CIRCULATION COMPARTMENT, ASPIRATOR MEANS IN THE CONDUIT SYSTEM FORCIRCULATING GAS FROM SAID RETURN CONDUIT THROUGH SAID CIRCULATIONCOMPARTMENT AND SAID SUPPLY CONDUIT TO SAID COMPARTMENT TO BE COOLED,SAID ASPIRATOR MEANS BEING ACTUATED BY GAS DISCHAGED FROM SAIDEXPENDABLE REFRIGERANT COMPARTMENT, AND A VENT FOR EXCESS GAS FROM THECIRCULATION SYSTEM.